Ok, I feel a bit like a newbie asking these questions, but I guess when it comes to fuel management I am a newbie. First, what's the difference between a AFC and SFMU? Can you run both, or is ok to run/have one or other. I understand an AFC allows you to adjust your fuel levels at various RPMs, but what exactly does a SFMU do? - specifically the Vortech since that's the one everyone talks about on here. Does the SFMU replace the Cartech FPR, or assist it? And, even more basic, where does it mount? Sorry, I just got to get this stuff straight in my head, I understand proper fuel tuning is essential to the longevity of your engine, and I am definately interested in that .....

Thanks, be kind


Yes officer, the windows are mirrored!

HRC Stage II w/FMIC

Yeah, the SFMU does replace the Cartech. You should be able to mount it wherever you mounted your Cartech. They're rising rate fuel pressure regulators. Basically they raise the fuel pressure according to boost: more boost = more fuel pressure = more fuel through the injectors.

The AFC is a different animal alltogether. It's a MAP value modifier. The manifold air pressure sensor as one of the main "inputs" the ECU uses to figure out how much fuel the engine should get. The AFC lets you adjust the MAP sensor value by percentage increments at different rpms - so you can fake the computer into giving you more or less fuel. You should be carefuel not to lean out the fuel too much under boost because a MAP signal that's modified to give less fuel ALSO advances the timing...which could be a bad thing under boost especially.


95 Eclipse RS : 5 speed
15.943 @ 86.48mph
Jeep TB writeup - http://www.dimensia.com:81/jimbo/JeepTBfor2gnt.html

>Ok, I feel a bit like a newbie asking these questions, but I
>guess when it comes to fuel management I am a newbie. First,
>what's the difference between a AFC and SFMU? Can you run
>both, or is ok to run/have one or other. I understand an AFC
>allows you to adjust your fuel levels at various RPMs, but
>what exactly does a SFMU do? - specifically the Vortech since
>that's the one everyone talks about on here. Does the SFMU
>replace the Cartech FPR, or assist it? And, even more basic,
>where does it mount? Sorry, I just got to get this stuff
>straight in my head, I understand proper fuel tuning is
>essential to the longevity of your engine, and I am definately
>interested in that .....
>
>Thanks, be kind

yes you can run both the sfmu and afc. the afc is the apexi one right? it is a fuel computer. from what i understand it dumps fuel in relation to rpm but it is not the best thing on turbo 2gnt since timing is advance if you lean out too much. davefl destroyed his built 420a engine leaning out the fuel with the afc and the cartech fpr (running larger injectors and the cartech can't handle that large a size of injectors). it is recommended that you only do large fuel curve changes with the sfmu and using the apexi to fine tune but make sure you have a data logger to check timing. imo, it is better to just stay with the sfmu, or get a better ems such as the greddy one. they (apexi and sfmu) both work with dumping fuel except the sfmu works by dumping a certain amount of fuel for every boost pressure it "sees." the sfmu replaces the cartech. they (cartech and sfmu) work by adding more fuel as boost pressure rises but the sfmu is just of a better quality and works much better (that's why we 2gnters replace them). the cartech and sfmu both mount in the engine bay, where the cruise control thing goes or you can mount them anywhere in the general hood location such as the windshild resevoir (some people have a hard time trying to fit the sfmu and while retaining cruise control function).

whoa that was long. have a nice day

-------jezreel

dammit, metal jim beat me!
-------jezreel

Ok, so I get the idea that I should really just go with the SMFU. I know you can get that at Summit. What's the deal with ordering the right bleeder valve and spring and all that?? Thanks.


Yes officer, the windows are mirrored!

HRC Stage II w/FMIC

The SFMU is adjustable to suit different fuel needs. The basic adjustments are the static fp and the rising rate. You want to set the static fp to the point where your stock injectors run while not boosting. You want to set the fp rising rate so that the fuel increases the correct amount per psi of boost. Lets say for example that you've got a system with stock injectors. Your static fp should be somewhere around 50 - so your injectors are happy when idling and not boosting. Lets say that your car likes 85 psi fuel pressure when you hit 7psi boost. In that situation, your rising rate is 5:1. 5psi fuel pressure increase per pound of boost. So what you have to do is get the right spring/disk combo to run that particular rising rate.

I don't know the specifics about the disks and springs(like what rising rates they yeild). The answer is going to depend on what injectors you have. I'm sure someone could help you out a bit more with that.


95 Eclipse RS : 5 speed
15.943 @ 86.48mph
Jeep TB writeup - http://www.dimensia.com:81/jimbo/JeepTBfor2gnt.html

If you are running stock injects, use the largest disk for the SFMU(it comes factory shipped with it inside), and the short, dark spring. You will have to put in the short, dark spring, becasue the SFMU ships with the longer silver spring. The shorter spring will let you run higher idle fuel pressures. Thats really all you need. That disk/spring combo gives you jsut the right amount of fuel up to 8 psi.

13.5 @108 MPH-2.2 60ft(stupid FWD!)
S16G @ 18 PSI/FMIC/Running on MegaSquirt II (Now with sequential
fuel injection)
My webpage: http://eclipsed4evr.home.comcast.net
-1998 Mitsubishi Eclipse RS-T- "Toy"
-1992 Plymouth Laser Turbo AWD(SOLD)
-2000 Honda CR-V(daily)

Ok, I think we're talking about 2 different things, but I didn't know that either, so thanks for the information Jim and Xtreme.

I thought I read on a post somewhere that there was like an additional valve or something (I could be way off here) that you needed to order as well when ordering the Vortech SMFU. Maybe a bleeder valve??? I don't know - I'm just winging it and hoping someone will know what the heck I'm talking about here.

Nice rims Jim ... where'd ya get em?


Yes officer, the windows are mirrored!

HRC Stage II w/FMIC